The application of well-dispersed nickel nanoparticles inside the mesopores of MCM-41 by use of a nickel citrate chelate as precursor

摘要

MCM-41 supported nickel catalysts were prepared with two different nickel precursors, viz. nickel nitrate and nickel citrate. The nature of the precursor significantly influenced the characteristics of the resulting catalysts, such as dispersion, average particle size and particle size distribution. With a weakly interacting precursor (nickel nitrate) only a small amount of nickel was deposited as nanoparticles inside the mesopores of the support material and the majority of nickel had aggregated into large crystallites at the external surface of the MCM-41 support. With a chelating nickel citrate precursor a Ni/MCM-41 catalyst having far more favourable properties was obtained. After incipient wetness impregnation the precursor salt is thought to leave a strongly adhering, thin film of nickel citrate inside the mesopores, which breaks up during the calcination treatment. As a result only very small nickel oxide nanoparticles were formed, which were located inside the mesopores of the support material. Reduction of these nickel oxide catalysts did not influence the characteristics of the support material, nor the dispersion and average particle size of nickel.